This invention relates to a resiliently supported connection unit for joining a transmission shaft to a transmission coupling element; the unit of the invention is particularly suitable for insertion into a motor vehicle transmission which connects the drive clutch to the gearbox or the power unit to an axle.
When they connect the power unit to an axle, transmissions of this type usually comprise a first shaft, a first end of which is connected by a coupling to said unit, and a second shaft, a first end of which is connected to the axle, while the second ends of said shafts are connected together by a universal joint. The second end of the first shaft must also be supported resiliently from the vehicle chassis, and this requirement is satisfied by providing a resilient support comprising a rolling bearing, the inner ring of which is keyed on to said end and the outer ring of which is housed in a bush coupled to an annular element of very deformable resilient material fixed to the chassis.
Consequently the second end of the first shaft must be connected to one of the two half couplings of the universal joint and simultaneously to the bearing of the aforesaid resilient support. In order to satisfy these two requirements, said end comprises a cylindrical portion which constitutes a seat for the inner ring of the bearing and a splined portion (or conical with tongue) arranged to engage in a corresponding splined bore of the hub of the aforesaid half coupling. Suitable shoulders and stop rings are necessary in order to axially lock said bearing both on the second end of the first shaft and inside said bush.
Certain drawbacks are encountered in said connection between the second end of the first shaft and said half coupling and in supporting said end.
The constructional method used for the said connection and support is complicated and therefore costly, requires special care for correct assembly, and if the rotating masses are not perfectly balanced can give rise to vibration.
In this respect, this constructional method requires numerous mechanical components and very precise machining operations on some of them (in particular on the splined coupling between the end of the shaft and the hub of the half coupling).